UN-Arab League envoy Kofi Annan singled out the government of Syrian President Bashar al-Assad in an appeal for an end to hostilities by both loyalist forces and rebel fighters seeking to oust him.

“I urge all forces whether governmental, opposition or others to put down their weapons and work with the United Nations monitors to consolidate the fragile cessation of violence,” Annan said in a statement. “The government in particular must desist from the use of heavy weapons and, as it has committed, withdraw such weapons and armed units from population centers and implement fully its commitments under the six-point plan.”

The latest violence comes only hours after the UN Security Council voted to approve Annan’s plan to send the extra 300 unarmed observers to Syria for three months, although Washington warned it might veto a new mandate for the mission.

Tank shelling and heavy gunfire were reported as the early morning raid was launched to crush al-Assad’s opponents in Douma, an outlying suburb of the Syrian capital, the activists reported.

Meanwhile, two UN advance team members set up base in Homs yesterday, a mission spokesman said, a day after they made their first visit to the central protest city since being deployed in Syria a week ago.

On Saturday, their visit to Homs included a stop in Baba Amr, a rebel hideout battered by a month-long army bombardment that killed hundreds, according to monitors, before it was retaken on March 1.

A YouTube video showed them meeting with activists who begged them to stay. Its authenticity could not be verified.

“Today is the first day since two months, exactly since Feb. 5 ... in Homs without shelling ... without killing, without fire,” one unidentified activist said in the footage.

“Because of that, we want you to stay. Please stay. This is what we want. When you come, shelling stops. When you come, killing stops,” he told the observers, who wore blue helmets and bulletproof vests marked “UN.”